Upgrade from (copied) beta version to legit version of W7.

So I installed a beta version of W7 Ultimate and it's displaying a watermark that says "this is not a legit version". I never had a legitimate product key.

I want to purchase a real version and upgrade appropriately.
Can I purchase an Upgrade license to Windows 7 Ultimate or do I have to purchase a Full version?

Also, what if I wanted to install Windows 7 Home Edition instead of the Ultimate version. If I did this, I assume I would have to install the Full version correct?

You can do a clean install using an Upgrade disc. The link I have supplied tells how. Basically, the install disc offers "Upgrade" or "Custom Install" choices... you select "Custom" but, you tell it NOT to Activate Automatically Online once installed. Then, as the instructions, say in the link, you run the disc, again, from w/in Windows (this time), select "Upgrade" (this time) & then, Activate when the upgrade (wink, wink) is done.

Note: Even Upgrade discs have the 2 choices.

You can do this using whatever flavour of 7 you want...since, it's a clean install, anyway.

Clean Install Windows 7 Using An Upgrade Disc

Cheers,
Drew